Band clutch assembly

ABSTRACT

An overrunning clutch comprising drive and driven clutch members, one of which has a V-groove into which the narrow tapered ends of a plurality of interfitting and overlapping clutch bands are disposed. An anchor is provided on the wide ends of the clutch bands which are disposed in slots formed in the other of such clutch members, where the slots are substantially longer than the anchors in a circumferential direction. The slots and anchor are conformably shaped so that as the load is applied the anchor is moving from one end of the slot to the other causes the bands to tighten into a snug pack just as the driving face of the anchor strikes the driving surface of the slot to thereby minimize deflections in the bands as well as radial forces in the drive member.

[ 1 Jan.9,1973

United states Patent 1 Austin et al.

[54] BAND CLUTCH ASSEMBLY Primary Examiner-Allen D. HerrmannAttorney-John A. Dienner et al.

[57] ABSTRACT An overrunning clutch comprising drive and driven clutchmembers, one of which has a V-groove into National-Standard Company,Niles, Mich.

[73] Assignee:

which the narrow tapered ends of a plurality of interfitting andoverlapping clutch bands are disposed. An

[22] Filed: July 29, 1971 anchor is provided on the wide ends of theclutch [211 App! 167327 bands which are disposed in slots formed in theother of such clutch members, where the slots are substantially longerthan the anchors in a circumferential direction. The slots and anchorare conformably shaped so that as the load is applied the anchor ismoving from one end of the slot to the other causes the bands to tighteninto a snug pack just as the driv- 0 C C 1/ wa 2 dR W6... 1 s l ".S 2 m9 "U 1 "9 m mh nuc .r. "a e nus L o W d S M U-mF HUM 555 [ii [56]References Cited UNITED STATES PATENTS ing face of the anchor strikesthe driving surface of the slot to thereby minimize deflections in thebands as well as radial forces in the drive member.

3,483,955 12/1969 Schelletal..........................l92/41S 9 Claims,5 Drawing Figures BAND CLUTCH ASSEMBLY BACKGROUND OF THE INVENTION Thepresent invention relates to clutch bands for band clutches of theoverrunning type.

The clutch band of this invention relates to the class of band clutchconstructions disclosed in U.S. Pat. No. 2,518,453, issued Aug. 15, l950to J. M. Dodwell. This patent discloses a band-type, free-wheelingclutch embodying drive and driven clutch members, one of which isprovided with a V-groove onto which the narrow tapered ends of aplurality of interfitting and overlapping clutch bands are disposed. Thewide ends of such clutch bands are anchored to the other of such clutchmembers so that upon rotation of the drive member in one direction adriven member is driven in the same direction through the engagement ofthe side edges of the narrow tapered ends of each clutch band with theside walls of the V-groove.

In operation of the overrunning or free-wheeling type clutches, uponrotation of the drive clutch member so as to tighten the clutch bandsaround the V- groove, the overlying portions of the clutch bands aredrawn tightly against the underlying portions of adjacent clutch bandsand the side edges of the clutch bands are urged into frictional drivingengagement with the side walls of the V-groove.

When the drive member of the above type of clutch is made of materialother than metal, such as thermosetting plastic, it is desirable tolimit the forces to a tangential direction. Previous design efforts toachieve a snug pack before a large load is applied, for example, US.Pat. No. 2,895,577 to J. M. Dodwell, are unsatisfactory because of theinherent bursting forces. The object of this invention is to apply atruly tangential load at the anchor and provide a snug pack to minimizedeflections in the bands for increasing the useful life of the clutch.

SUMMARY OF THE INVENTION In a preferred embodiment of the invention, aplurality of torque transmitting bands are disposed in overlapping andinterfitting relation between a drive member and a driven member. Eachband has an anchor formed on its wider end which conformably fits intoslots provided in the peripheral surface of the driven member. Each slothas a circumferential length greater than the thickness of the anchor. Aramp surface is provided so that when a load is applied the anchor movesacross the slot in such a fashion that the bands are brought into atight or compact pack before the anchors strike the end walls of theslots.

BRIEF DESCRIPTION OF DRAWING For a better understanding of the presentinvention reference may be had to the accompanying drawing in which:

FIG. 1 is a vertical sectional view of an overrunning type clutchconstructed in accordance with the principles of the present invention;

FIG. 2 is a top plan view of one of the clutch bands depicted in FIG. 1;

FIG. 3 is an enlarged view of FIG. 1 showing the anchor portion of oneof the clutch bands in overrun condition;

FIG. 4 is an enlarged view of FIG. 1 showing the anchor portion of oneof the clutch bands in driving condition; and

FIG. 5 is an enlarged view of the anchor portion of an overrunning typeclutch illustrating another embodiment constructed in accordance withthe principles of this invention.

DESCRIPTION OF ONE EMBODIMENT having a V-groove is depicted anddescribed in U.S.

Pat. No. 3,275,111, which issued to E. U. Lang et al. The driven clutchmember 14 is generally made of hardened steel or a similar materialcapable of withstanding the wedging action of the clutch band assembly16. v

The clutch band assembly comprises four identical clutch bands 17through 20 of generally spiral configuration which are positioned to bedisposed in an interfitting and overlapping arrangement. Each of theclutch bands are integrally formed as a one-piece structure preferablymade of spring steel stock.

The clutch band 17 is illustrated by way of example in FIG. 2, andincludes a wider or outer end portion 22 and a narrower or inner endportion or tip 24. An anchor 26 is provided at the end of wider endportion 22 and fits into one of the four identical slots 28 formed inthe drive member of FIG. 1. The anchor 26 is formed by folding a shortsegment of the wider end portion 22 upon itself into an arcuateconfiguration and brazing at 35 their common side together to define adriving face 30 and a release face 32. Slots 28 are formed as U- shapedcutouts in the inner surface of the drive member 12. The length of theslots 28 in a circumferential direction is substantially greater thanthe thickness of the anchors 26 to permit breathing of the clutch bands.By breathing is meant the radial loosening of the band assembly 16 toprovide low overrun torque. It will be noted that the driving face ofthe anchors 26 of the clutch bands is disposed along a generally radialline of the overrunning band clutch 10.

One of the important and critical features to the design of the FIG. 1embodiment is the provision of an inclined ramp surface 34 formed on theouter surface of the clutch band 18 at the base of anchor 26 between itsdriving face surface 30 and the wider end portion or outer end portion22. Ramp surface 34 is inclined at an oblique angle to a tangent to theinner radius of drive member 12 so that clutch band assembly 16 istightened before the driving face 30 of each clutch band engages thedriving sidewall of slots 28. By virtue of this arrangement, theforceapplied to the face 36 of the drive member is tangential and thebursting forces are substantially reduced.

In operation of the embodiment of FIG. 1, when the drive member 12begins to rotate in the direction indicated by the arrow, the clutchbands 17-20 tighten around the V-groove of the driven member 14. As thebands contract in a radial inward direction, the anchors move relativelycounterclockwise (as viewed in FIG. 1) towards the driving wall 36 ofslots 28. During this movement, ramp surface 34 rides against innercorner 38 of slots 28 to guide anchor 32 outwardly of slots 28 and theouter end portion 22 into engagement with a band immediately below theanchor. By virtue of the guiding function performed by ramp surface 34on each band, the clutch assembly 16 is tightened before the load isapplied to the driving face 30 of each anchor 26.

In those instances where the drive member 12 is made from a softermaterial, such as aluminum, the formation of the ramp surfaces 34 on thebands does not have to be as precise because the spring steel bands willdisplace corner 38 of each slot 28 until the proper hearing surface isprovided to guide the anchors 26 during tightening of the pack.

Referring to FIG. 5, there is shown an alternate means of guiding theanchors of clutch band assembly 16 during their clutching operation.Like parts to FIGS. 1 through 4 are designated by prime numbers. In thisembodiment, the slot 28' for each clutch band is provided with a rampsurface 50 formed as their rear wall. Ramp surface 50 of FIG. performsthe identical function as the ramp surface 34 in FIGS. 3 and 4. As theexerted on driving face 30' of each anchor has substantially no radialcomponent.

It will thus be seen that we have provided a novel and substantiallyimproved clutch construction. By providing ramp surface for guiding eachanchor out of the slots during tightening of the band assembly and bymaking the slots sufficiently wide in the circumferential direction, theanchor moves from one end of the slot to the other causing the bands tocontract into a snug pack just as the driving surface of the anchorstrikes the driving surface of the slot to thereby minimize deflectionsin the bands as well as radial forces in the drive member.

We claim:

1. In combination in an overrunning clutch having a drive clutch memberand a driven clutch member coaxially disposed with respect to the driveclutch member, one of said clutch members being provided with acircumferentially extending V-groove in the peripheral surface facingthe other clutch member, the other of said clutch members being providedwith an axially extending slot in its peripheral surface facing said V-groove, and a torque transmitting band comprising an outer end portion,an inner end portion and an anchor formed at the end of said outer endportion, said inner end portion extending into said V-groove and saidanchor contained within said slot, whereby relative rotation of saidmembers in one direction will cause said band to contract to transmittorque between said members, the improvement comprising the length ofsaid slot in a circumferential direction being substantially greaterthan the thickness of said anchor, both end walls of said slot and thedriving and releasing faces of said anchor extend in a generally radialdirection, and one of said slot and anchor having a ramp-surfaceinclined at an oblique angle to a tangent to the inner radius of saidother clutch member to guide said anchor along said oblique angle duringthe tightening of said band such that said driving face of said anchorengages the driving end wall of said slot just as the band is fullytightened.

2. In a combination as defined in claim 1, wherein said ramp surface isformed on said band at the base of said driving face of said anchor andis contiguous with said driving face.

3. In a combination as defined in claim 2, wherein said band is made ofhardened steel stock and said other clutch member is made of a softermaterial.

4. In a combination as defined in claim 1, wherein said anchor comprisesa fold formed at the end of said outer end portion, the outer oppositesurfaces of said fold defining said driving and release faces, wheresaid driving face extends generally along a radial line.

5. In a combination as defined in claim 1, wherein said ramp surface isformed by the rear wall of said slot that interconnects said end walls.

6. In combination in an overrunning clutch having a drive clutch memberand a driven clutch member coaxially disposed with respect to the driveclutch member, one of said clutch members being provided with acircumferentially extending V-groove in the peripheral surface facingthe other clutch member, the other of said clutch members being providedwith a plurality of spaced axially extending slots in its peripheralsurface facing said V-groove, and a plurality of torque transmittingbands, each of said bands comprising outer end portion and inner endportion with an anchor formed at the end of said outer end portion, saidinner end portion extending into said V-groove and said anchor containedwithin said slot, whereby relative rotation of said members in onedirection will cause said bands to tighten, the improvement comprisingthe length of each of said slots in a circumferential direction beingsubstantially greater than the thickness of said anchor, both end wallsof said slot and the driving and releasing faces of said anchor extendin a generally radial direction, and one of said slot and anchor havingramp surface inclined at an oblique angle to a tangent to the innerradius of said other clutch member to guide said anchor along saidoblique angle during the tightening of said bands such that said drivingface of said anchor engages the driving end wall of said slot just asthe bands are fully tightened.

7. In a combination as defined in claim 6, wherein said ramp surface isformed on each of said bands at the base of said driving face of saidanchor and is contiguous with said driving face.

8. In a combination as defined in claim 6, wherein said anchor for eachband comprises a fold formed at the end of said outer end portion, theouter opposite surfaces of said fold defining said driving and releasefaces, where said driving face extends along a generally radial line.

9. in a combination as defined in claim 6, wherein said ramp surface isformed by the rear wall of said slot that interconnects said end walls.

1. In combination in an overrunning clutch having a drive clutch memberand a driven clutch member coaxially disposed with respect to the driveclutch member, one of said clutch members being provided with acircumferentially extending V-groove in the peripheral surface facingthe other clutch member, the other of said clutch members being providedwith an axially extending slot in its peripheral surface facing saidV-groove, and a torque transmitting band comprising an outer endportion, an inner end portion and an anchor formed at the end of saidouter end portion, said inner end portion extending into said V-grooveand said anchor contained within said slot, whereby relative rotation ofsaid members in one direction will cause said band to contract totransmit torque between said members, the improvement comprising thelength of said slot in a circumferential direction being substantiallygreater than the thickness of said anchor, both end walls of said slotand the driving and releasing faces of said anchor extend in a generallyradial direction, and one of said slot and anchor having a ramp surfaceinclined at an oblique angle to a tangent to the inner radius of saidother clutch member to guide said anchor along said oblique angle duringthe tightening of said band such that said driving face of said anchorengages the driving end wall of said slot just as the band is fullytightened.
 2. In a combination as defined in claim 1, wherein said rampsurface is formed on said band at the base of said driving face of saidanchor and is contiguous with said driving face.
 3. In a combination asdefined in claim 2, wherein said band is made of hardened steel stockand said other clutch member is made of a softer material.
 4. In acombination as defined in claim 1, wherein said anchor comprises a foldformed at the end of said outer end portion, the outer opposite surfacesof said fold defining said drivIng and release faces, where said drivingface extends generally along a radial line.
 5. In a combination asdefined in claim 1, wherein said ramp surface is formed by the rear wallof said slot that interconnects said end walls.
 6. In combination in anoverrunning clutch having a drive clutch member and a driven clutchmember coaxially disposed with respect to the drive clutch member, oneof said clutch members being provided with a circumferentially extendingV-groove in the peripheral surface facing the other clutch member, theother of said clutch members being provided with a plurality of spacedaxially extending slots in its peripheral surface facing said V-groove,and a plurality of torque transmitting bands, each of said bandscomprising outer end portion and inner end portion with an anchor formedat the end of said outer end portion, said inner end portion extendinginto said V-groove and said anchor contained within said slot, wherebyrelative rotation of said members in one direction will cause said bandsto tighten, the improvement comprising the length of each of said slotsin a circumferential direction being substantially greater than thethickness of said anchor, both end walls of said slot and the drivingand releasing faces of said anchor extend in a generally radialdirection, and one of said slot and anchor having ramp surface inclinedat an oblique angle to a tangent to the inner radius of said otherclutch member to guide said anchor along said oblique angle during thetightening of said bands such that said driving face of said anchorengages the driving end wall of said slot just as the bands are fullytightened.
 7. In a combination as defined in claim 6, wherein said rampsurface is formed on each of said bands at the base of said driving faceof said anchor and is contiguous with said driving face.
 8. In acombination as defined in claim 6, wherein said anchor for each bandcomprises a fold formed at the end of said outer end portion, the outeropposite surfaces of said fold defining said driving and release faces,where said driving face extends along a generally radial line.
 9. In acombination as defined in claim 6, wherein said ramp surface is formedby the rear wall of said slot that interconnects said end walls.